Air pollution from automobiles, industrial plants, coal burning power plants, incinerators, and furnaces have created serious environmental pollution problems in the United States and other industrialized countries. These problems range from, depletion of ozone layer, greenhouse effect, foul odors to life threatening air pollution with heavy metals, toxic organics and acid rain.
Sulfur oxides, nitrogen oxides and chlorides which are emitted from a large number of industrial smoke stacks are converted into acids when exposed to moisture in the atmosphere. These acids are then returned to the earth in the form of acid rain which damages some vegetation and destroys aquatic life when the pH of lakes is dropped to low acidic levels.
Fish meal, paper mill and other plants discharge into the atmosphere chemicals with offensive and sometimes noxious odors that create problems to the people living near these plants. Incinerators for destroying toxic chemicals sometimes release exhaust gases into the atmosphere which are potentially dangerous to people living near where these incinerators are operating.
Most air pollution control systems presently available are either very expensive to install and operate or their air pollution control efficiency is questionable. Therefore, there is an urgent need for a simplified, cost effective system for controlling air pollution from industrial operation, incinerators and furnaces burning high sulfur coal and other polluting fuels. Such a cost effective pollution control system would allow the United States industry to be more competitive with developing countries where air pollution control has not been enforced as stringently as is in the United States.
The system of the present invention is designed to remove exhaust gases from a furnace during the process of burning old or excess pesticides, diesel oil, used motor oil, etc. The exhaust system from this furnace has been integrated with an artificial rock/plant marsh wastewater treatment system to provide a combined air and wastewater pollution control system.
The scientific basis for waste treatment in a rock/plant/ microbial filter is the cooperative growth of both the plants and the microorganisms associated with the plants. A major part of the treatment process for degradation of organics is attributed to the microorganisms living on and around the plant root systems.
Once microorganisms are established on aquatic plant roots, in most cases they form a symbiotic relationship with the higher plants. This relationship normally produces a synergistic effect resulting in increased degradation rates and removal of organic chemicals from the wastewater surrounding the plant root systems. Products of the microbial degradation of the organics are absorbed and utilized as a food source by the plants along with N, P, K and other minerals. Microorganisms also use metabolites released through plant roots as a food source. By each using the others waste products, this allows a reaction to be sustained in favor of rapid removal of organics from wastewater. Electric charges associated with aquatic plant root hairs also react with opposite charges on colloidal particles such as suspended solids causing them to adhere to the plant roots where they are removed from the wastewater stream and slowly digested and assimilated by the plant and microorganisms. Aquatic plants have the ability to translocate oxygen from the upper leaf areas into the roots producing an aerobic zone around the roots which is desirable in domestic sewage treatment. As water containing a variety of chemical pollutants flows underneath the surface of the rock/plant/ microbial filter, a high degree of water treatment and purification is achieved.
Many systems are available for removing waste from a fluid stream. One such system is disclosed in my U.S. Pat. No. 4,415,450, issued Nov. 15, 1983. The patent discloses a system and method for treat wastewater using microorganisms and vascular plants. The wastewater system includes a preliminary vessel in which an aerobic settling is carried out. A hybrid filter having a bed of particulate material is provided with the lower portion of the bed being inoculated with aerobic and faculative microorganisms and an upper portion being inoculated with aerobic microorganisms and having vascular aquatic plants growing therein. Fluid communication is provided between the preliminary vessel and the hybrid filter for conveying the effluent from the preliminary vessel to a bottom level of the hybrid filter for upflow therethrough.
U.S. Pat. No. 4,005,546 discloses a process for cleaning a waste fluid by first passing the fluid through a lime bed and then into a pond with algae.
Other patents which relate to the removal of waste from fluids include U.S. Pat. No. 2,222,310, 4,169,050 and 4,333,837 which disclose the use of aquatic plants to remove water from fluids. Similarly, U.S. Pats. No. 3,155,609 and 4,717,519 disclose the use of microorganisms to remove waste materials from a fluid.
There are also many systems available for treating plant exhaust gases or so called stack gases which generate various particulate and gaseous matter which contribute to air pollution. Hot or cold electrostatic precipitation, bag or filter bases, and mechanical precipitators have been used but are substantially limited to removal of particulate matter. Scrubbers, particularly wet scrubbers provide the most effective means for control of both particulate and gaseous pollutants.
The conventional wet scrubbers typically employ a vertical tower construction having a scrubbing zone therein in which the pollutants are removed. Typically such scrubbing zones include some form of restriction of the cross-sectional flow area of the stack gases, normally either baffles, trap or packed beds or a venturi. This restriction in the flow path through the scrubber necessarily results in an increased pressure drop as the stack gases move through the scrubber which in turn can be detrimental to the operating efficiency of the plant. U.S. Pat. No. 4,168,958 discloses the use of inclined baffles in the flow path through a vertically elongated chamber. The use of venturi scrubbers is disclosed in U.S. Pat. No. 4,344,920. The venturi scrubbers are in the form of one or more layers of solids disposed across the path of the gas and fluid flow. The layers are provided with impingement surfaces so that the gas is cleaned by agglomeration and absorption.
A system for treating stack gases without resulting to placing restrictions in the flow path of pollutant gases and particulate matter is disclosed in U.S. Pat. No. 4,102,982. However, this system requires the use of plurality of nozzles which are spaced at various stages along the flow chamber. One or more reagents are then sprayed at various stages into the chamber with the liquid droplets from the reagents moving across the path of the gases.
Applicant's pollution control system is a combined wastewater and air pollution control system which combines exhaust combustion gases with flowing wastewater which is then filtered through a rock/plant/microbial filtering system. Applicant's system uses a water stream to aspirate air containing odors and noxious chemicals underneath the bottom of a rock/plant/microbial filter. Such a system eliminates the need for baffles, venturis, and other restrictions in the flow path of the liquid and gases. Applicant also eliminates the need for nozzles for injecting reagents into the flow path at various stages along the flow path.
It is an object of the present invention, therefore, to provide a bioaquatic air pollution control system for a furnace or the like which prevents substantially dense, dirty aromatic smoke from polluting the atmosphere during operation.
It is another object of the present invention to provide such a bioaquatic air pollution control system with a filter system which relies upon the cooperative growth of aquatic plants and the microorganisms associated with the plants.
It is still a further object of the present invention to provide such a bioaquatic air pollution control system in which air pollutants are converted into or mixed with water pollutants for circulation through the filter system.
It is yet another object of the present invention to provide such a bioaquatic air pollution control system in which air pollutants and wastewater are combined rapidly and in a facile manner by an aspiration process for flow through such a filter system.